Propeller construction of an electric fan

Abstract

A fan assembly includes a propeller fixedly mounted on a shaft. The propeller has a rear side where fluid enters and a front side where fluid exits. The propeller has blades with an arcuate rib located on the front side of each blade. The arcuate rib may have curved outer surfaces at its outer ends and may be made up of portions formed about different centers of curvature.

What is claimed is: 
     
       1. A fan assembly comprising a propeller fixedly mounted on a shaft having a center line, said propeller having a rear side where fluid enters and a front side where fluid exits,   said propeller including a plurality of blades,   each of said blades having an arcuate rib located on the front side thereof,   each said arcuate rib being made of first, second and third curved portions integrally formed together,   said second curved portion being formed as an arc about said center line,   said first curved portion being formed as an arc about a first line parallel to said center line and located on one side of said center line, and   said third curved portion being formed as an arc about a second line parallel to said center line and located on the opposite side of said center line from said first line.   
     
     
       2. A fan assembly as recited in claim 1, wherein each of said arcuate ribs extends completely across the blade front side upon which it is located. 
     
     
       3. A fan assembly as recited in claim 1, wherein each of said blades has an outer edge and each of said arcuate ribs is positioned at said outer edge. 
     
     
       4. A fan assembly as recited in claim 1, wherein each of said blades has an outer edge and each of said arcuate ribs is positioned less than 30 mm from said outer edge.